Body parts, burnt-out vehicles and pools of blood were visible at the bomb site on the grounds of the School of Hygiene, which lies near the heart of the ancient northern city, an AFP reporter said.
It was not yet clear who carried out the attack but initial suspicion fell on Boko Haram, the Islamist extremists who have bombed many educational targets during a five-year uprising.
"So far 20 were taken to hospital and of that eight have been confirmed dead," Kano state police chief Aderele Shinaba told journalists at the scene.
The explosion came from a parking lot near the office of the school's provost, and while there were no classes on campus because of a term break, new students were reportedly on the grounds for registration.
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Access to the area was being tightly restricted by the military who had deployed in large numbers around the college, causing massive traffic build-up in the congested city.
Attacks blamed on Boko Haram were once a near-daily occurrence in Kano, but the security services have had some success in containing the violence in recent months.
Kano was hit by a suicide car bomb attack on May 19 in a mostly Christian area of the city, killing four people, including a young girl.
The military, which has been waging an offensive against Boko Haram in the northeast for more than a year, had claimed that the insurgents were on the run and no longer capable of attacking major population centres.
Kano was also put on edge earlier this month amid clashes that followed the controversial appointment of the area's new Muslim monarch.